They have to be certified by Mastercard/Visa, so no chance for open source. A few banks have their own implementation. Apart from mentioned samsung has its own version.

In general I strongly prefer open source, because lots of propertiary software will try to vendor lock you and then extract money from you, when it’s hard to escape for you.

In this case however I can change back to Connect or other any second, so amount of control this program has is extremely minimal and experience in exchange is better.

Informed choice is better than picking and following dogma, because dogma doesn’t work in some cases.